Mild hypothermia delays the development of stone heart from untreated sustained ventricular fibrillation--a cardiovascular magnetic resonance study.

Abstract

BACKGROUND:

'Stone heart' resulting from ischemic contracture of the myocardium, precludes successful resuscitation from ventricular fibrillation (VF). We hypothesized that mild hypothermia might slow the progression to stone heart.

METHODS:

Fourteen swine (27 ± 1 kg) were randomized to normothermia (group I; n=6) or hypothermia groups (group II; n=8). Mild hypothermia (34 ± 2 °C) was induced with ice packs prior to VF induction. The LV and right ventricular (RV) cross-sectional areas were followed by cardiovascular magnetic resonance until the development of stone heart. A commercial 1.5T GE Signa NV-CV/i scanner was used. Complete anatomic coverage of the heart was acquired using a steady-state free precession (SSFP) pulse sequence gated at baseline prior to VF onset. Un-gated SSFP images were obtained serially after VF induction. The ventricular endocardium was manually traced and LV and RV volumes were calculated at each time point.

RESULTS:

In group I, the LV was dilated compared to baseline at 5 minutes after VF and this remained for 20 minutes. Stone heart, arbitrarily defined as LV volume <1/3 of baseline at the onset of VF, occurred at 29 ± 3 minutes. In group II, there was less early dilation of the LV (p<0.05) and the development of stone heart was delayed to 52 ± 4 minutes after onset of VF (P<0.001).

CONCLUSIONS:

In this closed-chest swine model of prolonged untreated VF, hypothermia reduced the early LV dilatation and importantly, delayed the onset of stone heart thereby extending a known, morphologic limit of resuscitability.

• Authors: Vincent L Sorrell, Vijayasree Paleru, Maria I Altbach, Ronald W Hilwig, Karl B Kern, Mohamed Gaballa, Gordon A Ewy, Robert A Berg
• Journal: Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance (J Cardiovasc Magn Reson) Vol. 13 Pg. 17 (Mar 06 2011) ISSN: 1532-429X [Electronic] England
• PMID: 21375776 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: © 2011 Sorrell et al; licensee BioMed Central Ltd.

Topics

• Animals
• Disease Models, Animal
• Female
• Heart Arrest (diagnosis, etiology, physiopathology, prevention & control)
• Hypertrophy, Left Ventricular (diagnosis, etiology, physiopathology, prevention & control)
• Hypothermia, Induced
• Magnetic Resonance Imaging
• Random Allocation
• Swine
• Time Factors
• Ventricular Fibrillation (complications, diagnosis, physiopathology, therapy)
• Ventricular Function, Left
• Ventricular Function, Right